Highway safety fence cables



Oct. 8, 1968 THOMAS 3,404,526

HIGHWAY SAFETY FENCE CABLES Filed June 22, 1966 5 I 2 ifi 7 7 l /1 I 0 I s .e

A tlorneys 3,404,526 'P atented a. a, 1968 United States we e 3,404,526 HIGHWAY SAFETY FENCE CABLES Robert Albert Thomas, Kortrijk,"Belgium, asslgnor to Trefileries Leon Bekaert PVBA, Zwevegem, Belgium, a

"corporation of Belgium we Filed June 22, 1966,Ser. No.:559,471 Claims priority, application France, June. 25, 1965,

11 ch ns. icl. siz -149 ABSTRACT on THE DISCLOSURE The present invention relates generally to safety fences erected along highways and'the like roads to separate the various lanes and stop any vehicle which may leave its lane, and more particularly to an improved cable used such fences. I

' Heretofore, safety fences, including cables attached to posts, have been in use. The'cables used for this purpose are conventional cables made of a certain number of bare strands. These cables have many shortcomings. Struck by a motor vehicle, they aresubjected to vibrations that usually cause them to break. Due to the fact that the bare strands, visible on the cable surface, are made of metal, the damage caused by their being struck by motor vehicles are obviously considerable, especially since the bare cable hasnt a smooth outer surface. In addition, a bare cable is more likely to be broken if the resulting radius of curvature is very small when it IS bent.

The present invention overcomes these shortcomings. It relates to an improved cable, used in making safety fences to be erected along highways and like roads, which is characterized by the fact that all the strands which make up the cable are embedded in a coating of plastic or other suitable material which results in a smooth outer cylindrical surface. The coating, made of polyethylene, rubber or vinyl derivatives or other suitable substances, is a coating which is extruded around the metallic part of said cable.

The metallic part of the cable is preferably made up of a central strand, composed of a plurality of wires, and a plurality of other strands, wound helicoidally around the central strand. The extruded coating surrounds all the strands and fills in the cavities between the strands, and between the various wires.

Tests have proved that this cable gives satisfactory results and that the above-mentioned shortcomings of conventional cables are either completely overcome or at least considerably reduced. The cable, due to its coating as described above, vibrates much less than the conventional cable. The danger of it breaking is reduced because its vibration frequency is appreciably diminished. The coating also acts as a cushion, deadening the impact, and results in less damage to the vehicle which may strike the cable. Also, since the outer surface of the coating is smooth, the vehicle is not damaged as much as if conventional cables were used.

Finally, the cable provided with this coating can be bent around a cylinder of a diameter equal to at least four times the one of the cable without tearing the coating to pieces or breaking one of the wires which makes up the cable.

..:Various further and more specific purposes, features and advantages will clearly appear from the detailed description given below taken in connection with the accompanying drawings which form part of this specification and illustrate merely by way of example one em bodiment of the' device of the invention.

. In the following description and the-c1aims, parts will be identified by specific names for convenience, but such names are intended to be as generic in their application to similar parts as the art will permit. Like reference characters denote like parts in the several figures of the drawing.

In the drawing:

. FIG. 1 is a perspective view, partially in section, of the cable made in accordance with the invention;

FIG. 2 is a cross-section taken along the lines 22 in FIG. 1; and

FIG. 3 is a view of the minimum curvature to which a cablecan be subjected without being damaged.

Referring now more particularly to the drawing, the cable is made up of a metallic part A embedded in a coating B which is extruded around said part. Metallic part A is made up of a longitudinal central strand T and of a plurality of strands T wound helicoidally around the central strand T FIG. 1 of the drawing shows six strands T symmetrically arranged around strand T Each of strands T and T are composed of a plurality of steel wires 1, wound helicoidally.

The steel used for wires 1 may be a carbon steel of which the physical properties are the following ones:

Tensile strength kg./mm. 105 Elastic limit kg./mm. Between and Elongation measured on a wire of which the length is equal to ten times the diameter of the wire percent At least 2 The strands may also be composed of 7 wires of a diameter approximately equal to 1 mm.

Coating B may be made of any extrudable material, such as polyethylene, natural or synthetic rubber or a vinyl derivative or other suitable material.

The outside diameter d of metallic part A of the cable is preferably equal to 75% of the outside diameter D of the coated cable. As indicated by various tests, this ratio is preferable for obtaining an excellent penetration of the plastic material into the interstices and cavities of metallic part A, thereby giving the best adherence of the coating to said metallic part.

The composite cable, owing to its being coated and adhering to the metallic part as described above, advantageously combines the specific properties of tensile strength, elongation, and resistance to fatigue of the steel with the properties of the plastic coating B, thus considerably lowering the range of vibration frequencies and considerably increasing the resistance to friction between the safety fence and the striking motor vehicle on the one hand, and between the cable and the bushes or other elements afiixing the cable to the intermediate posts or to the end posts of the safety fence. This friction increase and the forces engendered contribute to the absorption of the energy accumulated by the motor vehicle striking the cable.

The cable, made up of a longitudinal strand and six peripheral strands symmetrically arranged around the core, composed of the central strand, has proved to be an excellent one for obtaining a good penetration of the coating into the interstices of said cable, as shown in FIG. 2, achieving a very strong adherence of the coating to the metallic part of the cable.

A coating of this type enables a cable so coated to be bent, as shown in FIG. 3, through an angle, equal to around a cylinder a having diameter E equal to four 3 times that of D of the coated cable, without breaking the coating B or breaking one of the wires 1. Consequently, the part of the cable struck by'the motor vehicle resists breaking.

The coating B also reduces the loss of resistance of the cable, resulting from winding the cable so that the resistance of the composite cable is increased as compared to a conventional all-metal cable of the same dimensions.

Having described the invention and illustrated its advantages, it will be understood by those skilled in the art after understanding the principle of the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended therefore in the appended claims to cover all such changes and modifications.

I claim:

1. A cable used in safety fences erected along highways or like roads comprising a central core, a plurality of strands wound around said core, and a coating, said coating surrounding said core and said strands whereby the coating fills in the spaces between said core and said strands and covers the outside of said cable.

2. A cable according to claim 1, wherein said core comprises a central wire and a plurality of wires wound around said central wire, said coating surrounding all of said wires.

3. A cable according to claim 1, wherein said strands comprise a central wire and a plurality of Wires wound around said central wire, said coating surrounding all of said wires.

4. A cable according to claim 2, wherein said strands comprise a central wire and a plurality of wires wound around said central wire, said coating surrounding all of said wires.

- 5. A cable according to claim 1, said coating being made of plastic material.

6. A cable according to claim 4, said coating being made of plastic material. a i

7. A cable according to claim 1, said coating being made of rubber material.

8. A cable according to claim 4, said coating bein made of rubber material.

9. A cable according to claim 1, wherein the outside diameter of the wound strands is equal to substantially 75% of the outside diameter of the coated cable.

10. A cable according to claim 4, wherein the outside diameter of the wound strands is equal to substantially 75% of the outside diameter of the coated cable.

11. A safetyfence for a highway or like road comprising at least one cable, said cable comprising a central core, a plurality of strandswound around said core, and a coating consisting of a substantially shock absorbing material, said cable substantially embedded in said coating, said coating providing said cable with a continuous, smooth surface and means simultaneously filling the spaces between said strands and said core.

References Cited Riggs 57-149 FRANK J. COHEN, Primary Examiner.

D. E. WATKINS, Assistant Examiner. 

